A signal-off type photoelectrochemical immunosensor for detecting carcinoembryonic antigen based on TiO2 NRs/BiOI heterojunction and SiO2/PDA-Au inhibitor

A novel signal-off photoelectrochemical (PEC) immunosensor for sensitive and specific detection of carcinoembryonic antigen (CEA) is proposed. This proposed PEC sensor uses titanium dioxide nanorods (TiO2 NRs)/ bismuth iodide (BiOI) heterojunction (TiO2 NRs/BiOI) as the photoactive matrix in which SiO2/PDA-Au is used as the labeled secondary marker. The TiO2 NRs/BiOI heterojunction has excellent visible light absorption capacity and the photoelectric signal is about 3.5 times of pure TiO2 NRs, which also has efficient carrier separation and transfer capabilities. In addition, SiO2/PDA-Au bring a dual inhibitory effect due to SiO2/PDA with a big spatial block and Au nanoparticles with a high visible light absorption capacity, which significantly improves the sensitivity of the constructed sensor. This PEC immunosensor demonstrates great sensitivity, selectivity, and stability, which shows a detection range of 0.005-100 ng mL(-1) and a detection limit as low as 0.00167 ng mL(-1). The constructed PEC immunosensor also has good performance in the analysis of real human serum samples.

Automated summary

The photoelectrochemical (PEC) immunosensor proposed in this study utilizes TiO2 NRs/BiOI heterojunction as the photoactive matrix and SiO2/PDA-Au as the labeled secondary marker, demonstrating great sensitivity, selectivity, and stability for the analysis of real human serum samples.